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Commit a399a805 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

time: jiffies_delta_to_clock_t() helper to the rescue 



Various /proc/net files sometimes report crazy timer values, expressed
in clock_t units.

This happens when an expired timer delta (expires - jiffies) is passed
to jiffies_to_clock_t().

This function has an overflow in :

return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);

commit cbbc719f (time: Change jiffies_to_clock_t() argument type
to unsigned long) only got around the problem.

As we cant output negative values in /proc/net/tcp without breaking
various tools, I suggest adding a jiffies_delta_to_clock_t() wrapper
that caps the negative delta to a 0 value.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarMaciej Żenczykowski <maze@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: hank <pyu@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 79cda75a

include/linux/jiffies.h

+6 −0
Original line number Diff line number Diff line
@@ -303,7 +303,13 @@ extern void jiffies_to_timespec(const unsigned long jiffies, 
extern unsigned long timeval_to_jiffies(const struct timeval *value);

extern void jiffies_to_timeval(const unsigned long jiffies,

			       struct timeval *value);



extern clock_t jiffies_to_clock_t(unsigned long x);

static inline clock_t jiffies_delta_to_clock_t(long delta)

{

	return jiffies_to_clock_t(max(0L, delta));

}



extern unsigned long clock_t_to_jiffies(unsigned long x);

extern u64 jiffies_64_to_clock_t(u64 x);

extern u64 nsec_to_clock_t(u64 x);

net/bridge/br_fdb.c

+1 −1
Original line number Diff line number Diff line
@@ -312,7 +312,7 @@ int br_fdb_fillbuf(struct net_bridge *br, void *buf, 


			fe->is_local = f->is_local;

			if (!f->is_static)

				fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->updated);

				fe->ageing_timer_value = jiffies_delta_to_clock_t(jiffies - f->updated);

			++fe;

			++num;

		}

net/bridge/br_stp_timer.c

+1 −1
Original line number Diff line number Diff line
@@ -170,5 +170,5 @@ void br_stp_port_timer_init(struct net_bridge_port *p) 
unsigned long br_timer_value(const struct timer_list *timer)

{

	return timer_pending(timer)

		? jiffies_to_clock_t(timer->expires - jiffies) : 0;

		? jiffies_delta_to_clock_t(timer->expires - jiffies) : 0;

}

net/core/rtnetlink.c

+1 −1
Original line number Diff line number Diff line
@@ -618,7 +618,7 @@ int rtnl_put_cacheinfo(struct sk_buff *skb, struct dst_entry *dst, u32 id, 
		       long expires, u32 error)

{

	struct rta_cacheinfo ci = {

		.rta_lastuse = jiffies_to_clock_t(jiffies - dst->lastuse),

		.rta_lastuse = jiffies_delta_to_clock_t(jiffies - dst->lastuse),

		.rta_used = dst->__use,

		.rta_clntref = atomic_read(&(dst->__refcnt)),

		.rta_error = error,

net/ipv4/igmp.c

+5 −2
Original line number Diff line number Diff line
@@ -2435,6 +2435,8 @@ static int igmp_mc_seq_show(struct seq_file *seq, void *v) 
		struct ip_mc_list *im = (struct ip_mc_list *)v;

		struct igmp_mc_iter_state *state = igmp_mc_seq_private(seq);

		char   *querier;

		long delta;



#ifdef CONFIG_IP_MULTICAST

		querier = IGMP_V1_SEEN(state->in_dev) ? "V1" :

			  IGMP_V2_SEEN(state->in_dev) ? "V2" :
@@ -2448,11 +2450,12 @@ static int igmp_mc_seq_show(struct seq_file *seq, void *v) 
				   state->dev->ifindex, state->dev->name, state->in_dev->mc_count, querier);

		}



		delta = im->timer.expires - jiffies;

		seq_printf(seq,

			   "\t\t\t\t%08X %5d %d:%08lX\t\t%d\n",

			   im->multiaddr, im->users,

			   im->tm_running, im->tm_running ?

			   jiffies_to_clock_t(im->timer.expires-jiffies) : 0,

			   im->tm_running,

			   im->tm_running ? jiffies_delta_to_clock_t(delta) : 0,

			   im->reporter);

	}

	return 0;